# ET.HargreavesSamani

##### Hargreaves-Samani Formulation

Implementing the Hargreaves-Samani formulation for estimating reference crop evapotranspiration.

##### Usage

```
# S3 method for HargreavesSamani
ET(data, constants, ts="daily", …)
```

##### Arguments

- data
A list of data which contains the following items (climate variables) required by Hargreaves-Samani formulation:

*Tmax*,*Tmin*- constants
A list named

`constants`

consists of constants required for the calculation of Hargreaves-Samani formulation which must contain the following items:*Elev*- ground elevation above mean sea level in m,*lambda*- latent heat of vaporisation = 2.45 MJ.kg^-1,*lat_rad*- latitude in radians,*Gsc*- solar constant = 0.0820 MJ.m^-2.min^-1.- ts
Must be either

`daily`

,`monthly`

or`annual`

, which indicates the disired time step that the output ET estimates should be on. Default is`daily`

.- …
Dummy for generic function, no need to define.

##### Details

This formulation provides a single calculation method with no alternatives available.

##### Value

The function prints a calculation summary to the screen containing the following elements:
- ET model name and ET quantity estimated
- Evaporative surface with values of albedo
- Time step of the output ET estimates (i.e. the value of argument `ts`

)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including *mean*, *max* and *min* values.

Daily aggregated estimations of Hargreaves-Samani reference crop evapotranspiration.

Monthly aggregated estimations of Hargreaves-Samani reference crop evapotranspiration.

Annually aggregated estimations of Hargreaves-Samani reference crop evapotranspiration.

Monthly averaged estimations of daily Hargreaves-Samani reference crop evapotranspiration.

Annually averaged estimations of daily Hargreaves-Samani reference crop evapotranspiration.

Name of the formulation used which equals to `Hargreaves-Samani`

.

Type of the estimation obtained which is `Reference Crop Evapotranspiration`

.

##### References

McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. *Estimating actual, potential, reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis*. Hydrology and Earth System Sciences Discussions, 9, 11829-11910.

Hargreaves, G.H.Samani, Z.A. 1985, *Reference crop evapotranspiration from ambient air temperature*. American Society of Agricultural Engineers.

##### See Also

##### Examples

```
# NOT RUN {
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")
# Call ET.HargreavesSamani under the generic function ET
results <- ET.HargreavesSamani(data, constants, ts="daily")
# }
```

*Documentation reproduced from package Evapotranspiration, version 1.10, License: GPL (>= 2)*